With the improvement of people's living level and the development of communication technology, users not only need the mobile communication service such as a conventional telephone, a message, etc. but also have demand for the mobile multimedia service. Because the existing IP multicast technique is not suitable for a mobile communication network to implement the mobile multimedia service, a multimedia broadcast/multicast services (MBMS) is proposed by the third generation mobile communication partner program (3GPP). A data source is provided in the mobile communication network for performing point-to-multi-points service for many user equipments, sharing network source, and improving the utilization rate of network source. The MBMS has two means: broadcast and multicast. The MBMS not only can achieve broadcast and multicast for pure text with low rate, but can also achieve broadcast and multicast for multimedia with high rate.
Based on the packet network of WCDMA/GSM, MBMS adds some new function entities into the packet network of WCDMA/GSM such as broadcast multicast service centre (BM-SC) for introducing an MBMS function into an existing package area function entity, e.g. service general packet radio service supporting node (SGSN), gateway general packet radio service supporting node (GGSN), radio network controller (RNC), and user equipment (UE). A new logic share channel is defined to achieve air interface resource share in 3GPP standard. Schematic diagram illustrating the system architecture of the MBMS system is shown in FIG. 1. The MBMS service module is set in the RNC connected to the UE. The RNC, SGSN, GGSN, BM-SC is connected one after another to form the MBMS service system.
Based on the above-mentioned MBMS service system, a complete flow for the MBMS service can be described as follows:                1, User subscription: establishing a relation between a UE and a service provider;        2, Service announcement: informing the UE of information related to the MBMS service;        3, Joining: joining in a multicast group to UE and informing a network UE of receiving multicast data;        4, Session start: indicating that the BM-SC is ready and preparing for sending data;        5, MBMS notification: informing the UE that MBMS data is ready for sending;        6, Data transfer: transmitting data at user level;        7, Session stop: deciding to end data transmission within a certain period and releasing bearing resource by the BM-SC;        8, Leaving: UE leaving the multicast group and not receiving service data any more.        
The step 1, 3, and 8 are indispensable for multicast service.
MBMS radio transmission bearing means can be generalized by point-to-point (PtP) and point-to-multipoint (PtM). Under the PtP, service is born point-to-point, that is, each UE transmits service data separately. Under the PtM, service is born point-to-multipoint, that is, many UEs transmit service data at the same time.
During the establishment process of an MBMS service, after receiving a service establishment request initiated by a core network, the radio network needs to calculate the number of UEs and determine the specific radio bearing means according to the utilization situation of the current service. When the statistic result shows that the number of UEs exceeds the UE number threshold when the PtP mode is transformed to the PtM mode, it is determined that the PtM transmission means is adopted in the MBMS multicast service, and the relevant transmission means is noticed to the UE. If the number of UE does not achieve the transformation threshold from the PtP to the PtM, the PtP transmission means will be adopted. During the transmission of MBMS service, real-time statistic is still needed for the number of UE and the statistic result is used to dynamically adjust the radio transmission bearing means of the current MBMS.
The type of UE is not considered in the prior art whereas different types of UE may correspond to different media resource format in some cases. Using one format for all UEs to transmit the media resource may cause that some media resource cannot be played or used on some UE resulting in the waste of network resource.